[lirc] preventing multiple connections to the lirc socket

on @topfs2 recommendation (PR #5268 ): separate PR of this fix for the Gotham tree

Details to this PR also explained in forum:
http://forum.xbmc.org/showthread.php?tid=202592

This fix should prevent that Kodi connects to the same socket multiple times if XBMC.LIRC.Start is called multiple times.